Prostaglandin E2‐like activity of 20:3n‐9 platelet lipoxygenase end‐product

Abstract

5,8,11‐Icosatrienoic acid (20:3n‐9), a fatty acid associated with platelet hyperactivity, was oxygenated by platelet lipoxygenase. The end‐product of this pathway was purified by high‐performance liquid chromatography (HPLC) and characterized as 12‐hydroxy‐5,8,10‐icosatrienoic acid [12‐OH‐20:3(5,8,10)] by capillary gas‐liquid mass spectrometry. When tested upon platelet aggregation, 12‐OH‐20:3(5,8,10) exhibited a biphasic effect. At low concentrations (below 5 × 10⁻⁷ M) it potentiated aggregation but inhibited it at higher levels, a pattern similar to that obtained with prostaglandin E₂. However, since the amounts of 12‐OH‐20:3(5,8,10) generated under thrombin stimulation are in the range of concentrations with potentiating effects, it seems that the 12‐OH derivative is responsible for the hyperaggrebility of 20: 3n‐9‐rich platelets.